Histopathological Investigation of Clinically Non-Affected Perilesional Scalp in Alopecias Detected Unexpected Spread of Disease Activities

In a 2014 study involving 50 Japanese patients with alopecia, researchers found that 66% of clinically non-affected perilesional scalp specimens exhibited microscopic abnormalities. Among the 16 patients with alopecia areata (AA), 62.5% showed an increased telogen ratio, vellus hair count, and miniaturization. In the 19 scarring alopecia (SA) cases, 26.3% had perifollicular inflammatory cell infiltration. The study suggested that in SA, a treatment area should extend 2-3 cm from the lesion margin, and it provided standard hair pathology values for East Asians. These results demonstrate that disease activity in alopecia may spread beyond visible affected areas, indicating the need for histopathological examination of perilesional scalp regions in the management of hair loss conditions.